Polysiloxane polymer networks are well known, including networks made from silanol terminated polysiloxanes where the network is made with polymers having a bimodal distribution of molecular weights. Silanol terminated polysiloxanes of different molecular weights can be crosslinked with tetramethyl orthosilicate. One problem with these networks are their low modulus. The modulus can be increased by adding reinforcing fillers such as fumed silica, but the resulting polysiloxane networks are not transparent.
It is the object of this invention to make bimodal polysiloxane networks of higher modulus without resorting to adding proportionately more short chain polysiloxanes and without adding reinforcing silica fillers.